Machine tool hand

ABSTRACT

Provided is a machine tool hand including a body portion that is mounted so as to be attachable to and detachable from a spindle of a machine tool, and that is provided with a flow path connected to a coolant-liquid supply path formed in the spindle; and two or more hand members that are attached to the body portion such that at least one of the hand members is pivotable about a prescribed axis, and that are capable of gripping an object therebetween by being closed. The flow path is provided with discharge ports via which a coolant liquid supplied from the coolant-liquid supply path is discharged toward surfaces of the hand members that are exposed to an outside, and a pressure of the coolant liquid causes an opening operation or a closing operation of the hand members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Applications Nos.2019-147321 and 2020-115692, the contents of which are incorporatedherein by reference.

FIELD

The present disclosure relates to a machine tool hand.

BACKGROUND

There is a known gripping device that drives a plurality of hand membersso as to be opened and closed by utilizing a coolant liquid supplied toa spindle of a machining center (for example, see Publication ofJapanese Examined Utility Model Registration No. 3206020).

This gripping device includes: a cylinder into which a coolant liquidsupplied to a spindle is injected; a piston that is movably disposed inthe cylinder and that is moved by the pressure of the coolant liquid;and a plurality of hand members that are pivotably coupled to thepiston.

SUMMARY

An aspect of the present disclosure is a machine tool hand including: abody portion that is mounted so as to be attachable to and detachablefrom a spindle of a machine tool, and that is provided with a flow pathconnected to a coolant-liquid supply path formed in the spindle; and twoor more hand members that are attached to the body portion such that atleast one of the hand members is pivotable about a prescribed axis, andthat are capable of gripping an object therebetween by being closed. Theflow path is provided with discharge ports via which a coolant liquidsupplied from the coolant-liquid supply path is discharged towardsurfaces of the hand members that are exposed to an outside, and apressure of the coolant liquid causes an opening operation or a closingoperation of the hand members.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view showing a machine tool hand according to anembodiment of the present disclosure, in a state in which a pair of handmembers are closed.

FIG. 2 is a front view showing the machine tool hand in FIG. 1 , in astate in which the pair of hand members are opened.

FIG. 3 is a front view showing a state in which a workpiece is grippedby the machine tool hand in FIG. 1 .

FIG. 4 is a longitudinal sectional view showing the machine tool hand inFIG. 2 .

FIG. 5 is an enlarged longitudinal sectional view showing the flow of acoolant liquid in the machine tool hand in FIG. 2 .

FIG. 6 is an enlarged longitudinal sectional view showing a firstmodification of the machine tool hand in FIG. 1 , in a state in which apair of hand members are closed.

FIG. 7 is an enlarged longitudinal sectional view showing the machinetool hand in FIG. 6 , in a state in which the pair of hand members areopened.

FIG. 8 is a front view showing a second modification of the machine toolhand in FIG. 1 , in a state in which a pair of hand members are opened.

FIG. 9 is a front view showing the machine tool hand in FIG. 8 , in astate in which the pair of hand members are closed.

FIG. 10 is a longitudinal sectional view showing the machine tool handin FIG. 9 .

FIG. 11 is a front view showing a machine tool hand according to anotherembodiment of the present disclosure, in a state in which a pair of handmembers are closed.

FIG. 12 is a front view showing the machine tool hand in FIG. 11 , in astate in which the pair of hand members are opened.

DETAILED DESCRIPTION

A machine tool hand 1 according to an embodiment of the presentdisclosure will be described below with reference to the drawings.

As shown in FIGS. 1 and 2 , the machine tool hand 1 according to thisembodiment includes a body portion 2 and a pair of hand members 3.

The body portion 2 includes: a distal end portion 4 that is formed in acuboid block shape; and a cylindrical shaft portion 5 that is disposedcloser to the base end than the distal end portion 4 is, and that is formounting the body portion 2 so as to be attachable to and detachablefrom a spindle 100 of a machine tool. As shown in FIG. 4 , the shaftportion 5 is provided with a flow path 7 that extends along a centralaxis from an opening 6 at one end. When the shaft portion 5 is attachedto the spindle 100, the opening 6 is connected to a coolant-liquidsupply path 110 provided in the spindle 100, and a coolant liquidsupplied from the coolant-liquid supply path 110 is allowed to flow intothe flow path 7.

The pair of hand members 3 are disposed on both sides of the distal endportion 4 of the body portion 2, and are individually attached to thebody portion 2 so as to be pivotable about two parallel pivot axes(axes) A, B extending along a plane orthogonal to the central axis ofthe shaft portion 5.

As shown in FIG. 4 , the flow path 7 provided in the body portion 2 isbranched into branched flow paths 8 in two directions in the distal endportion 4. The branched flow paths 8 are individually branched in thedirections toward the individual hand members 3. The branched flow paths8 have discharge ports 9 opening at two locations on each side surfaceof the distal end portion 4. The total of the opening areas of the fourbranched flow paths 8 and the discharge ports 9 thereof is set to besubstantially equal to the cross-sectional area of the flow path 7 inthe shaft portion 5.

Gears 10 that rotate about the pivot axes A, B are fixed to therespective hand members 3. The gears 10 fixed to the two hand members 3mesh with each other.

In addition, a coil spring (urging member) 11, which urges the handmembers 3 in the closing direction by means of an elastic restoringforce, is bridged between the two hand members 3.

In this embodiment, opposing side surfaces of the pair of hand members 3are disposed so as to face the positions where these opposing sidesurfaces close off the discharge ports 9 provided in the distal endportion 4 of the body portion 2.

In a state shown in FIG. 1 in which the pair of hand members 3 areclosed, the side surfaces of the individual hand members 3 are disposedclosest to the discharge ports 9, at positions where the side surfacessubstantially close off the individual discharge ports 9. In a stateshown in FIG. 2 in which the pair of hand members 3 are opened, the sidesurfaces of the individual hand members 3 are slightly inclined so as tobe separated from the discharge ports 9 as a result of the individualhand members 3 pivoting about the pivot axes A, B, and gaps are formedbetween the body portion 2 and the hand members 3.

The individual hand members 3 are constantly urged in the closingdirection by means of the elastic restoring force of the coil spring 11.In other words, in a state in which a workpiece (object) W is not heldbetween the hand members 3 and the coolant liquid is not supplied intothe flow path 7, the side surfaces of the individual hand members 3close the discharge ports 9 in the body portion 2 by means of theelastic restoring force of the coil spring 11.

Then, when the coolant liquid is supplied into the flow path 7, theindividual hand members 3 are pushed by the coolant liquid dischargedfrom the discharge ports 9 and are caused to pivot in directions inwhich the hand members 3 are separated from each other against theelastic restoring force of the coil spring 11. The pressure of thecoolant liquid discharged from the discharge ports 9 is, for example,0.4 MPa to 2 MPa.

In the figures, reference sign 12 indicates an end stopper that abutsagainst the hand members 3 at the open positions and that restrictsfurther movement of the hand members 3 by means of elastic deformation.In addition, reference sign 13 indicates an elastic member, such as asponge, that comes into contact with the workpiece W and is elasticallydeformed when the workpiece W is gripped.

The operation of the thus-configured machine tool hand 1 according tothis embodiment will be described below. In the description hereinafter,since the machine tool hand 1 according to this embodiment is formedsymmetric laterally, there will be described only for one side, and thedescription for the other side will be omitted.

The machine tool hand 1 according to this embodiment is, for example,stored as one of the tools in a tool magazine of a machine tool and isattached to the spindle 100 in place of another tool, as needed orperiodically, by an automatic tool changing device (not shown) providedin the machine tool.

For example, when it is necessary to supply a workpiece W to a chuckprovided on a rotary table, to change the orientation of a workpiece W,or the like, the machine tool hand 1 is attached to the spindle 100.

Then, in a state in which the machine tool hand 1 is attached to thespindle 100, with the hand members 3 thereof directed downward, themachine tool hand 1 is raised or lowered in accordance with an elevatingoperation of the spindle 100.

As shown in FIG. 1 , in the case of gripping a workpiece W disposedvertically below the machine tool hand 1, the machine tool hand 1 islowered by lowering the spindle 100, and as shown in FIG. 2 , the pairof hand members 3 are brought into an open state by supplying thecoolant liquid from the spindle 100. Then, in a state in which theworkpiece W is disposed between the pair of hand members 3, as shown inFIG. 3 , the pair of hand members 3 are brought into a closed state bystopping the supply of the coolant liquid, thus allowing the workpiece Wto be gripped.

In this case, with the machine tool hand 1 according to this embodiment,when the pair of hand members 3 are brought into the open state, thecoolant-liquid supply path 110 utilized during processing of theworkpiece W is utilized, and the coolant liquid is supplied into theflow path 7 in the body portion 2 from the coolant-liquid supply path110 through the opening 6. By doing so, the coolant liquid supplied intothe flow path 7 in the body portion 2 is discharged from the dischargeports 9 opening in two directions and presses the side surfaces of theindividual hand members 3, thereby allowing the individual hand members3 to pivot about the pivot axes A, B.

Because the flow path 7 in the body portion 2 is open to the outside atthe discharge ports 9, the coolant liquid discharged from the dischargeports 9 flows along the side surfaces of the hand members 3 whilepressing the side surfaces of the hand members 3, and flows downwardfrom the distal ends of the hand members 3. The coolant liquid that hasflowed down is recovered in a coolant tank (not shown) and is allowed tocirculate in the same manner as in the processing.

Although fine chips or the like become mixed into the coolant liquid atthis time, in this embodiment, the coolant liquid for opening andclosing the hand members 3 is released to the outside from the dischargeports 9 of the flow path 7 in the body portion 2, and the hand members 3are caused to pivot by the flow energy during the release. Therefore,because the coolant liquid is not supplied into a closed space, there isan advantage in that it is possible to perform handling, etc. of aworkpiece W without causing a malfunction due to chip clogging even whenfine chips or the like become mixed into the coolant liquid.

In addition, with the machine tool hand 1 according to this embodiment,the pair of hand members 3 are constantly urged in the closing directionby means of the elastic restoring force of the coil spring 11; thus, thehand members 3 can be easily brought into the closed state by stoppingthe supply of the coolant liquid. In addition, because the gears 10meshing with each other are fixed to the pair of hand members 3, thereis an advantage in that it is possible to place the gripping position ofthe workpiece W at the center as a result of the pair of hand members 3pivoting by the same angles distributed from the center.

In addition, when the pair of hand members 3 are brought into the openstate, as shown in FIGS. 4 and 5 , the hand members 3 pivot about thepivot axes A, B, and the side surfaces pushed by the coolant liquid areeach disposed so as to form an angle larger than 90° relative to thedischarge direction. With this configuration, a guide means for thecoolant liquid is formed, and the coolant liquid is allowed to flowalong the side surfaces while being guided toward the distal ends of thehand members 3. As a result, there is an advantage in that portions forgripping the workpiece W can be washed with the coolant liquid everytime the pair of hand members 3 are opened.

In addition, in this embodiment, the flow path 7 in the body portion 2is branched into the four branched flow paths 8, and the cross-sectionalarea of each of the branched flow paths 8 and the discharge ports 9 isset to be ¼ of the cross-sectional area of the flow path 7. Thus, thecross-sectional area of flow does not change between the flow path 7 andthe branched flow paths 8, and loss can be reduced.

Note that, in this embodiment, the side surfaces of the hand members 3are pushed by the coolant liquid itself discharged from the dischargeports 9. Alternatively, as shown in FIGS. 6 and 7 , spherical metal(e.g., steel) bodies (movable bodies) 15 movable in the branched flowpaths 8 in the vicinity of the discharge ports 9 may be disposed.

As shown in FIG. 6 , the spherical body 15 has a diameter size smallerthan an internal diameter of the branched flow path 8; and a gap ofwhich the coolant liquid flows out is formed between the spherical body15 and an inner surface of the branched flow path 8. In the figures,reference sign 16 indicates a cylindrical body that forms an inner wallof the branched flow path 8 in a movable range of the spherical body 15.Reference sign 17 indicates an abutting member embedded in the sidesurface of each of the hand members 3 opposing to the discharge ports 9.

In order to suppress aberration of the body portion 2 and the handmembers 3 caused by contacts with the spherical bodies 15 when the bodyportion 2 and the hand members 3 are made lighter in weight by using analuminum alloy or the like, the cylindrical body 16 and the abuttingmember 17 are constituted by a hard material, for example, steel. Theabutting members 17 are secured to the hand material 3 in a replaceablematter by engagement and disengagement of screws.

Reference sign 12 indicates an end stopper that restricts a pivot angleabout pivot axis A or B of the hand members 3. The end stopper 12according to this embodiment stops pivoting of the hand members 3 byabutting the hand members 3 at a pivot angle where a discharge amount ofthe spherical body 15 from the discharge port 9 is equal to or less thana hemisphere. In FIGS. 6 and 7 , illustrations of the coil spring 11 areomitted.

When the coolant liquid is supplied into the flow path 7 from thecoolant-liquid supply path 110, a portion of the coolant liquid branchedto the two branched flow paths 8 pushes the spherical body 15 to movethe spherical body 15 to a side of the discharge port 9, and theremainder is discharged to the outside from the discharge port 9 via thegap between the spherical body 15 and the inner surface of the branchedflow path. Each of the spherical bodies 15 pushed by means of a pressureof the coolant liquid pushes the corresponding abutting member 17 of thecorresponding hand member 3 by protruding from the correspondingdischarge port 9 to the outside, thus causing the hand members 3 topivot about the respective pivot axes A, B. By doing so, distal ends ofthe two hand members 3 are opened.

Since the center of the spherical body 15 is held at the inner side thanthe discharge port 9, a minimum value of the coolant-liquidcommunication cross-sectional area formed by the gap between the innersurface of the branched flow path 8 and the spherical body 15 remainsconstant without depending on the pivot angle of the corresponding handmember 3. That is, since the pressure applied to the spherical body 15from the coolant liquid does not vary by the pivot angle of thecorresponding hand member 3, the hand members 3 can be opened with alarge stable force only by increasing the pressure of the coolantliquid. As a result, there are advantages in that a spring rigidity canbe improved, a gripping force for the workpiece W can be improved, andtherefore a stable handling can be realized.

In addition, by providing the gap around the spherical body 15, thecoolant liquid can be discharged to the outside from the correspondingdischarge port 9 without confining the coolant liquid in the flow path7. By doing so, it is possible to prevent malfunction caused by cloggingwith chips or the like contained in the coolant liquid.

In addition, an amount of the cooling liquid discharged from thedischarge port 9, of the coolant liquid supplied into the flow path 7,can be restricted by means of the corresponding spherical body 15. Bydoing so, there are advantages in that it can be prevented to dischargea large amount of the coolant liquid when the hand members 3 are opened,and an operator can easily confirm the state of the hand members 3 andthe workpiece W visually.

In the above aspect, a spherical shape was illustrated as a shape of themovable object, however, it is not limited thereto. An arbitrary shape,such as a columnar shape, a shell-type shape, or the like, may beemployed. Even when the columnar shape or the shell-type shape isemployed, a posture change of the movable body can be suppressed, andthe minimum value of the communication cross-sectional area formed bythe gap between the inner surface of the branched flow path 8 and themovable body 15 can remain substantially constant.

Note that the gears 10 for synchronizing pivoting of the two handmembers 3 need not be provided in this embodiment. In addition, althougha case in which the two hand members 3 are both caused to pivot aboutthe pivot axes A, B has been illustrated as an example, one of the handmembers 3 may be fixed and only the other one may be caused to pivot.This configuration also allows gripping of the workpiece W.

In addition, although the machine tool hand 1 including the pair of handmembers 3 has been illustrated as an example in this embodiment,alternatively, the present invention may be applied to a machine toolhand 1 including three or more hand members 3.

In addition, although four branched flow paths 8 are provided in thisembodiment, alternatively, it suffices that two or more branched flowpaths 8 be provided for causing two or more hand members 3 to pivot.

In addition, the hand members 3 may have any shape, and a plurality ofmachine tool hands 1 having different shapes may be prepared accordingto the shapes of workpieces W to be gripped.

In addition, although the coolant liquid is supplied in the case ofopening the hand members 3 in this embodiment, alternatively, as shownin FIGS. 8 to 10 , the coolant liquid may be supplied when the handmembers 3 are to be closed.

In this case, a coil spring (urging member) 14 that constantly urges thehand members 3 in the opening directions may be employed.

Next, a machine tool hand 20 according to another embodiment of thisdisclosure will be described below. In the description of thisembodiment, identical reference signs are assigned to portions havingconfigurations common to those in the machine tool hand 1 according tothe above embodiment, and a description thereof will be omitted.

As shown in FIG. 11 , the machine tool hand 20 according to thisembodiment includes a body portion 21, a movable member 22, and a pairof hand members 23.

A distal end portion 24 of the body portion 21 is provided with a groove25 that is arranged at the center of the width direction and thatextends along the central axis of the shaft portion 5 from an endportion opposite to the shaft portion 5. The flow path 7, which extendsalong the central axis of the shaft portion 5 from the opening 6 at oneend of the shaft portion 5, is provided with the discharge port 9 at agroove bottom of the groove 25.

The movable member 22 is disposed inside the groove 25 and is supportedso as to be movable only in a direction along the central axis of theshaft portion 5 with respect to the distal end portion 24. A coil spring(urging member) which is not shown is bridged between the movable member22 and the distal end portion 24. The movable member 22 is constantlyurged in a direction closer to the discharge port 9 by means of theelastic restoring force of the coil spring.

The movable member 22 is moved closer to the groove bottom, thus beinglocated at a position where the discharge port 9 is closed.

The pair of hand members 23 are supported to the movable member 22 insuch a way that each proximal end thereof can pivot about a pivot axis(axis) C perpendicular to the central axis of the shaft portion 5. At anintermediate position of each of the hand members 23, an elongated guidehole 26 is provided so as to obliquely extend toward a direction of thedistal end of the corresponding hand member 23 and a direction away fromthe central axis of the shaft portion 5.

A pin 27 that is provided on a side surface of the distal end portion 24and that extends parallel to the pivot axis C, is inserted into each ofthe guide holes 26.

The operation of the thus-configured machine tool hand 20 according tothis embodiment will be described below.

When the coolant liquid is supplied into the flow path 7, the coolantliquid flows and is discharged toward the movable member 22 from thedischarge port 9. The discharged coolant liquid is sprayed into themovable member 22 that is being disposed at the position where thedischarge port 9 is closed. By doing so, the movable member 22 is movedtoward a direction away from the discharge port 9 along the central axisof the shaft portion 5.

In response to the movement of the movable member 22, each of the handmembers 23 connected to the movable member 22 is moved along alongitudinal direction of the corresponding guide hole 26 with respectto the corresponding pin 27 secured at the distal end portion 24. Bydoing so, as shown in FIG. 12 , the hand members 23 pivot about thepivot axis C, and thus the distal ends of the hand members 23 areopened.

When the supply of the coolant liquid is stopped, the movable member 22is pulled back toward the direction closer to the discharge port 9 bymeans of the elastic restoring force of the coil spring. By doing so, inresponse to the movement of the movable member 22, each of the handmembers 23 pivots in a direction in which the distal end is closed.Thereby, it is possible to grip the workpiece W between the hand members23.

Thus, similarly to the machine tool hand 1 according to the firstembodiment, the machine tool hand 20 according to this embodiment canalso open and close the pair of hand members 23 by means of the coolantliquid discharged from the discharge port 9. There is an advantage inthat, even when fine chips or the like become mixed into the coolantliquid, by releasing the coolant liquid to the outside from thedischarge port 9, it is possible to perform handling, etc. of theworkpiece W without causing a malfunction due to chip clogging.

In addition, it is possible to cleanse the hand members 23 with thecoolant liquid discharged from the discharge port 9 flowing along thesurface of the hand members 23 every time the pair of hand members 23are opened.

Note that, in this embodiment, the case where the hand members 23 areopened by discharging the coolant liquid was illustrated. Reversely, thehand members 23 may be closed by discharging the coolant liquid.

The invention claimed is:
 1. A machine tool hand comprising: a bodyportion comprising a flow path, the body portion configured to bedetachably mounted to a spindle of a machine tool and the flow pathconfigured to fluidically connect with a coolant-liquid supply pathformed in the spindle; and two or more hand members that are attached tothe body portion such that at least one of the two or more hand membersis pivotable about a prescribed axis, wherein the two or more handmembers, when in a closed state, are capable of gripping an objecttherebetween, wherein the flow path is provided with discharge ports viawhich a coolant liquid supplied from the coolant-liquid supply path isdischarged from the body portion to impinge upon surfaces of the two ormore hand members, the surfaces being disposed to an outside of the bodyportion, and wherein a pressure resulting from the coolant liquidimpinging upon the surfaces causes an opening operation of the two ormore hand members or a closing operation of the two or more handmembers.
 2. The machine tool hand according to claim 1, furthercomprising an elastic member which opposes, through an elastic restoringforce, the pressure resulting from the coolant liquid impinging upon thesurfaces.
 3. The machine hand tool according to claim 2, wherein theelastic member is a coil spring.
 4. The machine tool hand according toclaim 1, wherein, in an open state, the surfaces that are disposed tothe outside of the body portion are angled to guide the coolant liquidtowards a distal end of the two or more hand members.
 5. The machinetool hand according to claim 4, wherein, in the open state, the surfacesform an angle larger than 90 degrees relative to a discharge directionof the discharge ports.
 6. The machine tool hand according to claim 1,wherein the body portion comprises a cylindrical shaft portion thatdetachably mounts to the spindle, and wherein the body portion is formedhaving a cuboid block shape at a distal end opposite the cylindricalshaft portion.
 7. The machine tool hand according to claim 6, whereinthe flow path extends along a central axis of the cylindrical shaftportion.
 8. The machine tool hand according to claim 6, wherein a firstof the two or more hand members is attached to the body portion and ispivotable about a first axis, and wherein a second of the two or morehand members is attached to the body portion and is pivotable about asecond axis which extends parallel to the first axis.
 9. The machinetool hand according to claim 6, wherein the flow path provided in thebody portion branches into a plurality of branched flow paths beforeterminating at the discharge ports.
 10. The machine tool hand accordingto claim 9, wherein the discharge ports open on side surfaces of thedistal end portion of the body portion, perpendicular to a central axisof the cylindrical shaft portion.
 11. The machine tool hand according toclaim 9, wherein a total of opening areas of the branched flow paths andthe discharge ports thereof is equal to the cross-sectional area of theflow path in the cylindrical shaft portion.
 12. A machine toolcomprising: a spindle, and the machine tool hand according to claim 1,wherein the machine tool hand is able to be attached to the spindle inplace of another tool.